1. Field of Use
This invention relates generally to apparatus for separating liquid droplets from gas in which they are suspended.
In particular, it relates to apparatus, such as an oil separator or oil filter assembly, used for separating and recovering oil droplets suspended in pressurized hot refrigerant gas circulating in a refrigeration system.
2. Description of the Prior Art
In a typical large commercial refrigeration system, a suitable refrigerant gas such as freon or ammonia is compressed (and heated) in a reciprocating or rotary compressor and is then supplied to a condensor, to an evaporator and back to the compressor for recompression and recirculation. The compressor employs oil therein for sealing, cooling and lubrication purposes. Some of this oil forms a fog (or vaporizes if it becomes hot enough) and mixes with the refrigerant being circulated. This is undesirable for several reasons. Lost oil (on the order of one gallon per day, for example) needs to be replaced to ensure proper compressor operation. Furthermore, condensation and collection of oil in other parts of the system, such as in the evaporator, causes loss of system efficiency and needs to be removed periodically. Filling and/or draining the system are costly and time consuming procedures and result in system down-time.
Therefore, it is customary to employ oil separator apparatus in the system, usually between the compressor and the condenser, to separate the oil and return it to the compressor by means of a pump and to allow the substantially oil-free refrigerant gas to continue on to the condenser. It should be noted that reciprocating and rotary compressors typically operate at gas temperatures of about 300.degree. F. and 175.degree. F., respectively, and therefore oil vaporization and condensation are more likely to occur in reciprocating compressors.
The following U.S. and foreign patents illustrate prior art separators for separating liquids from gas; U.S. Pat. Nos. 4,111,815; 4,053,290; 3,802,160; 3,791,105; 3,300,951; 1,912,235; 1,463,990; 780,682; British Pat. No. 921,753; Italian Pat. No. 273,917.
Some of the problems inherent in prior art separators are: unduly complex designs making manufacturing and servicing difficult, numerous joints which need to be sealed but still offer possibilities for gas and oil leakage, inefficient filter elements and arrangements requiring relatively frequent filter element replacement or system draining.